1. Field of Invention
This invention relates generally to devices which provide a seal between a rotatable shaft and a housing and, more particularly, to such devices which accomplish sealing utilizing the dynamic effect of rotating parts.
2. Prior Art
Various types of sealing devices are utilized to provide a seal along a rotatable shaft between the interior and exterior of a housing. In the case of pumps and other such devices; lubricating oil, the product being pumped, or other substances are contained under pressure within the housing. Sealing elements help to contain the substances within the housing and prevent them from contaminating the environment outside the housing. Often, the temperature, pressure and/or chemical composition of the substance within the housing renders the substance extremely dangerous should it escape into the environment.
In such applications, the most commonly used sealing device is a mechanical seal. Generally, a mechanical seal comprises a rotating assembly (commonly known as a rotor assembly) fixed to the shaft, and a stationary assembly (known as a stator), against which a moving surface on the rotor bears, thus establishing a seal. In order to provide the desired sealing effect, the rotor and stator must be precisely fixed in their relative positions. The position of the mechanical seal is fixed by a housing known as a stuffing box, which has studs protruding therefrom generally parallel to the shaft. Bolted to the stuffing box studs is a gland housing. The stuffing box and gland housing, when bolted together, house the seal rotor and stator. The sealing surfaces between the rotor and stator will eventually wear to a point of failure, necessitating inspection and replacement. Premature failure can result from misalignment, product destruction of sealing surfaces and defective sealing surfaces as well as other causes. Seal failure will often result in rupture, wherein lubricants and/or products are spilled or sprayed under pressure into the environment. Aside from the obvious danger to personnel, seal failures often have severe economic consequences such as clean-up costs, plant down time, pump and seal replacement costs and lost product costs.
Other types of sealing devices are currently on the market. Failure of such other devices will have similar results to those stated above. All sealing devices currently on the market will have a certain degree of leakage, and designs are currently built around an accepted leakage factor.